Captain America, Iron Man, Hulk, Thor, and Hank Pym, who has his stingers and his ant-controlling helmet, adapted to grow as well as shrink with him. (I know Wasp is in the pic, but she's not in the battle. Current versions all, and completely bloodlusted.
Superman, Batman, Wonder Woman, Flash (Barry Allen), and Green Lantern (Hal Jordan). Current versions, except for Hal, who is back from the dead and has his ring back. Completely bloodlusted. Both teams know the other team's abilities.
Here's my view on it. Thor and Hulk gang up on Superman, and win, due to Thor's magic. Flash runs up and takes out Hulk, but is taken out himself by Thor. Meanwhile, Batman is fighting Cap, and they're mostly even, but Hank causes ants to crawl up into Batman's suit, distracting him and giving Cap the chance to deliver the killing blow. Iron Man is quickly taken out by GL. Wonder Woman takes on the weakened Thor, and it ends up in a draw with both dying. Hank turns giant, and gives GL a decent fight, but is beaten. Cap takes on GL next, and his ring runs out of energy when he's just about to beat Cap, causing the Avengers to take the win.